Received:
28
October
2003
Accepted:
18
May
2004
Published online:
9
November
2004

Abstract

Isomeric states in 210-215Ra have been populated by the decay of the compound nuclei 216, 220Ra produced in irradiations of 204, 208Pb with 12C at Elab = (68-136)MeV. Published values for γ-ray energies and half-lives were confirmed for 212m-215m Ra. Our data for 210m Ra agree with the γ-energies and the half-life measured at the RITU separator, University of Jyväskylä (Finland). Its decay pattern is complex. Two series of γ-rays of Eγ = 96.7, 774.6, 578.0, 604.5keV and Eγ = 96.7, 602.1, 750.5, 604.5keV were observed. A half-life of ( 2.36±0.04)μs was measured. The isomeric state is attributed to an 8+ state at E* = 2053.8keV. A previously unknown isomeric state was assigned to 211m Ra. It has a half-life of (4.0±0.5)μs and it decays by emission of γ-rays with energies of 396.1keV and 802.0keV. It is attributed to a 13/2+ state at E* = 1198.1keV.